O > > > > You might want to try ignoring the check in dev.c and testing > > to see if there is a performance gain. It wouldn't be hard to test > > a modified version and validate the performance change. > > Yes. With my patch, there is a huge performance gain by increasing MTU to 64K. > And it seems the only way to do this is by S/G. > > > You could even do what I suggested and use skb_checksum_help() > > to do inplace checksumming, as a performance test. > > I can. But as network algorithmics says (chapter 5) > "Since such bus reads are expensive, the CPU might as well piggyback > the checksum computation with the copy process". > > It speaks about onboard the adapter buffers, but memory bus reads are also > much slower > than CPU nowdays. So I think even if this works well in benchmark in real > life > single copy should better. >
The other alternative might be to make copy/checksum code smarter about using fragments rather than allocating a large buffer. It should avoid second order allocations (effective size > PAGESIZE). -- Stephen Hemminger <[EMAIL PROTECTED]> - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
